An eBay seller has 5 used Garmin Geko 201 GPS's for a nice price of $29 each. These GPS's are great for the UL walker that doesn't rely on GPS, but does value having one as a backup tool for tougher conditions.
They're about 3oz with batteries and useful because they give you your coordinates so you can locate yourself on a topo map, and you can also input waypoints (good for packrafting take-outs and finding passes in white out conditions).
The 201 doesn't have as good of a battery life as the 301 version, but most likely you'll be leaving it off 98% of the time anyways.

